Posted
by
kdawsonon Friday October 22, 2010 @03:43PM
from the eclipsing-actinic-pinprick dept.

The Bad Astronomer writes "Exoplanets orbiting binary stars have been discovered before, but NN Serpentis is a weird system even in that category. One star is a red dwarf in an incredibly tight orbit around a white dwarf. The white dwarf used to be a star like the Sun but became a red giant as it died, engulfing the red dwarf. Now the two orbit each other almost as closely as the Moon orbits the Earth. Explaining how the two newly detected exoplanets survived such an event is very difficult, and astronomers think they may have actually formed from the material expelled by the star as it died."

The view from that planet must be nice. Unfortunately, given the orbit and the fact that the other star is a red giant, the planet isn't likely to be very habitable. But it isn't that far away, only about 1500 light years. I still find it really amazing that we're actually living in a time where we can map the planets in other star systems. And that we're able to do so from the comfort of Earth orbit is nothing short of amazing. And of course, all of this means that we are getting better estimates for the Drake equation as well. Everything used to be a complete unknown. But now the major room for variation are the biological variables not the astronomical ones.

And of course, all of this means that we are getting better estimates for the Drake equation as well. Everything used to be a complete unknown. But now the major room for variation are the biological variables not the astronomical ones.

OTOH, since the biological variables are such unknowns, the equation is still largely useless for any real-life calculation. I mean, Fi (the fraction that develop intelligent life) can range anywhere from almost 0 to almost 100% and L (the length of time such a civilization releases a signal to space) could be very long, but could also be extremely short, since we now see that on Earth most signals are not lost to space because the signals are focused to satellites and back to Earth.The time that we release signals to space was actually quite short and is almost over.

For reflection purposes you don't need an equation. I can just tell you that there are many, many stars and planets, but the chance that a planet will have life on it is low. Given the large distances involved the chance to contact said life forms is low. See? All clear. We have an equation to try and quantify the variables - Is the number of stars is larger than the chance to develop intelligent life is small? Since we don't have any useful estimates, the equation is just a fancy way to write down what can

Hypothetical, at least in the case of planets, although every bit of new evidence that comes in does seem to support the hypothesis.

but the chance that a planet will have life on it is low.

Even more hypothetical, and much less supported by the evidence. In fact, we have at least one other place in this system alone where the existence of life is considered reasonably plausible (Europa [wikipedia.org]), and several more (Mars before the freeze, Venus before the meltdown, several other outer system moons) where it's considered plausible that life may have once existed, and a coup

First of all I'll just say that I was giving general examples and that is why I left out most of the components of the equation and didn't refer to each one in particular.Second, I have to say that you also strengthened my point: All the information we have about the probability of life in other planets is hypothetical. Putting it into an equation doesn't make that information more concrete.And no, the equation doesn't make things more efficient. Every time Drake's equation comes up people write the equatio

Completely disregarding how it's (presumably) not possible in this case, etc, it makes me wonder--if intelligent life developed with stars like that, what sort of mythologies would they have to explain their suns' eternal duel?

I mean, hell, we romanticize dawn and dusk, and the moon, and fear the nighttime and eclipses, and we're paranoid about the tiny pinpricks of light that are the stars, thinking they hold great sway over us. They probably wouldn't know that if those two stars actually collided, their lives would all be over--or if they guessed, they wouldn't know why or how--but would they be given personas? What sort of stories would they make up? What would they think the two eclipses symbolized?

I guess as a writer and daydreamer it's just a fascinating idea to toy with.

at 10 on earth you are constantly travelling with 1021.7837 mph (1644.4 km/h). For an alien living on a much slower planet this could be insane! Also, the speed of our solar system within the galaxy is about 220 km/s. Point is, life could be anywhere. It adapts.

Yes, those ideas have been considered. The idea of having life based on other elements was proposed by chemists and biologists in the first place. Silicon is the only one of the ideas that is that plausible simply because it acts chemically similar to carbon. However, it doesn't have nearly as much flexibility in the sort of compounds it can form which makes it unlikely. Most metals don't have anything resembling the necessary chemistry (in general you want something that is on the staircase between metals and non-metals. Otherwise you can't get a large variety of chemistry). EMF is just stupid and seems to be the sort of thing that comes out simply from people thinking of "energy based lifeforms" in Star Trek and other scifi. This idea makes so little sense that it isn't clear where to start explaining what is wrong with it. There might be weird exotic forms of life that we haven't considered but there's not much we can do about it until we have a lot more ideas what is out there, so that doesn't amount to anything scientifically useful. But by all means, continue convincing yourself that your comments somehow buck some scientific establishment that hasn't thought about any of these issues.

it's about 10 minutes long, and pretty fascinating. They poured 10 tons of concrete into an ant colony, let the concrete die, and then excavated around it. The resulting concrete form is pretty amazing. It's pretty spooky how efficient and awesome it is. I would imagine that if we saw something that looked like this little mini-city on another planet, that we'd assume that it was designed and built by some pretty intelligent lifeforms with some higher level of intellect. Why don't we think of ants this way? What kinds of alien life are all around us that we don't even know?

I think from an "extraterrestrial life" point of view, there wouldn't be a lot of difference between finding something like ants and finding something like us.

I've always felt the "will it develop intelligence" thing is overstated. Most scientists expect that if we find life on Mars or wherever, it will be in the form of some simple single-celled bacteria-like creature, perhaps simple multi-celled plant slime at best. If we discover large, complex eukaryotic life, with limbs, internal organs, hunting, matin

nope, that's just more carbon chauvinism talk, because silicon is so similar to carbon. Actually sulfur, arsenic and phosphorus (with nitrogen) can also form long complex chains and rings and can have protein analogs.

Not with any kind of long term stability. And you need some kind of solvent that works pretty university. This cuts the number of usefully compounds down drastically --to the point where you don't have anything left.

There is a reason even our man made synthetic materials are based on carbon.

Then there is a another thing to consider. If you have phosphorus etc around, you have *more* carbon around. Carbon is produced in quite large amounts in stellar processes and is quite common in the galaxy.

yes, can have long term stability in right environment, the biochemists who posited the possibilities actually put some thought into their suggestions.

no, don't need "solvent that acts universally", that's just supposition. our own earth life may have started in clay, a proper supporting matrix (might even be gaseous) doesn't have to be a universal anything.

If you want things to happen you do. Without mobility you don't get any interesting chemistry without geological timescales. Its needs to be somewhat "universal" so that you can have more than one/few compounds/"proteins" with mobility.

There is a some literature on this. And you also left out the part where, if you have these other elements, you also have carbon.

Oh and clay is only clay when there is a lot of water in it.... guess what makes things "soluble" in a clay matrix, and permit transport.

I'm certain they have. However, considering that life forms based upon "weird alternatives" might be sufficiently exotic that we wouldn't even recognize them as life at first, it seems to make sense to *start* by looking for combinations that we already know work and for which we have established minimum requirements.

Requisite/. car (keys) analogy: Think of it this way...when you lose your car keys, do start by looking in likely places you may have left them, or do you start by looking in weird, alternative locations? Likewise, if we have established that life is most likely to occur in conjunction with liquid water, it makes the most sense to took for extra-terrestrial life in areas where liquid water exists.

Yes, but since there's zero evidence of life based on things other than carbon, and there's tons of carbon-based life here on Earth, and carbon is such a versatile element for creating compounds, the ET biologists are focusing on lifeforms we would recognize as life.

When we start seeing Horta creatures, then we'll start thinking more about silicon-based lifeforms.

What strikes me is that as we gain a better understanding space, the more bizarre we discover it to be. In this case, we have proposed theories on how what we are now seeing may have come into existence, but the author is clear that we are only choosing which is less implausible. With the same consideration, I've wondered if we will recognize life if we found it.

I am neither astronomer, astrophysicist, nor celestial mechanic. But, when the white dwarf was in it's red giant phase, engulfing the red dwarf, it seems to me the red dwarf would have just been vacuuming up whatever red giant material was near it as it sailed along on its path. Would that have caused friction that would make it spiral in closer? Also, if part of the mass of the other star in its red giant phase was beyond the orbit of the red dwarf, then it would have had less gravitational pull on the

A star like this that leaves behind a white dwarf is not one that underwent a supernova. I think most of what you're saying is quite reasonable. The red dwarf would still be attracted to the red giant's centre of mass, but if it was completely engulfed in the red giant you'd expect it to migrate closer to the red giant's core very quickly. The accreted material would probably be predominantly helium I think, which would add to the red dwarf's mass but possibly not make it hotter/more luminous (I don't know